The Photoshop plugin prints with the wrong orientation when using roll paper.

Comments from Wiki Discussion Section:

Prints unnecessarily waste roll paper

The Photoshop plugin can print the wrong way on a roll without ever telling the user or noting it in a preview (11x17 going the long way on a 17 inch roll with 6 inches of white space, for example). The page preview for this can look identical to the preview going across the roll!

In order to avoid this, always use the Print Area Layout 1 preview mode, and follow the instructions provided here:
Conserve Roll Paper

Borderless prints are too large / too small - how do I check the orientation before printing?

[The problem] occurs for me when the borderless button is checked in the plugin. I see that when I check that button the previews stop shifting from portrait to landscape and back, but they do shift when you've got the button unchecked.

This is a problem of bad interface design, but it can be overcome when you know where to look. A full description of what to look for and what to do is available here:
Borderless Print Orientation